UN's Ban says Mandela was a 'giant for justice'

UN chief Ban Ki-Moon paid homage Monday to Nelson Mandela as a giant for justice, equality and human rights, and said the world has lost a hero.

Ban visited the Nelson Mandela Centre for Memory in Johannesburg, where mourners lit candles and signed a book of condolences in memory of the democracy icon who died on Thursday.

"The world mourns the loss of Nelson Mandela -- one of the towering figures of our time and indeed of any time," he told journalists after a whirlwind tour of the centre, which houses a collection of historical documents on Mandela's life.

"We join together in sorrow for a mighty loss and in celebration of a mighty life.

"He was a giant for justice and equality and human rights."

Ban recounted meeting South Africa's first black president at his home in 2009, and thanking Mandela for his contribution to peace and freedom.

He said he was struck by the Nobel laureate's human decency.

"What he said at the time struck me so deeply. He said: 'Well it's not only me, there were hundreds and hundreds of known and unknown people who worked for that cause'.

"I was so deeply moved and touched. What he said is still guiding me."